Improvement in blackboard-rubbers



UNI'IED STATES PATENT OFFICE.

JOSEPH B. WALKER5 OF LOUISVILLE KENTUCKY.

IMPROVEMENT IN BLACKBOARDRUBBERS.

Specification forming Part o f Letters Patent N0. 154,357, dated August25, 1874; application fi1ed J anuary 2, 1874.

T0 all whom z't may concem Be il: known that I, JOSEPH B. WAL'KER, of

.the eity of Louisville, in the eounty 0f J efi'erson and State 0fKentucky, have invented a new Rubber t0 Erase Ohalk-Marks fromBlackboards and other surfaees and do hereby declare that the,fol'lowing is a full am]. exact; description of the same.

I take a block -0f wood of any convenient size, say six inehe s long,two inches wide, and one und a half ineh thick. I 01113 01 mold theedges t0 giVe conveuient hold for grasping With the fingers, als shownin the aeeonhpany-- ing drawing. I next groove theunder surface to admitfolds 0f heavy eloth (as sail-duck) '00 form a brush'or rubber; I thenstop the pores 0f the wood with a solution of gelatine, am].

bing is efl'eeted by the ends of the threads,

and arranged as deseribed, so that the threads ran diagonaflly 130 thje=i=ubbing-surt'aee, substantially as aindfor. th@ purpose set forth.

J OS. B. WALKER. Witnesses:

FRANK O. ANDERSON, F. A. COOPER.

